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Date: Tue, 11 Sep 2012 10:41:02 -0400
From: Vivek Goyal <vgoyal@redhat.com>
To: Lars Ellenberg <lars.ellenberg@linbit.com>
Cc: NeilBrown <neilb@suse.de>, Kent Overstreet <koverstreet@google.com>,
        Jens Axboe <axboe@kernel.dk>,
        Philipp Reisner <philipp.reisner@linbit.com>,
        linux-kernel@vger.kernel.org, Tejun Heo <tj@kernel.org>,
        Christoph Hellwig <hch@lst.de>, drbd-dev@lists.linbit.com
Subject: Re: [Drbd-dev] FLUSH/FUA documentation & code discrepancy
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On Tue, Sep 11, 2012 at 10:25:01AM +0200, Lars Ellenberg wrote:

[..]
> "To enforce write-after-write dependencies, you *have* to drain the
> queue (do we have a generic interface available for that?),
> or at least wait for the completion of all the requests you
> (potentially) depend upon, before even submitting the dependent request.

I think you need to wait for all previous IOs (you are dependent on) to finish.

Thanks
Vivek